Silicone Resin Film, Method of Preparing Same, and Nanomaterial-Filled Silicone Composition

ABSTRACT

A method of preparing a silicone resin film, the method comprising coating a release liner with a nanomaterial-filled silicone composition comprising a hydrosilylation-curable silicone composition and a carbon nanomaterial, and heating the coated release liner at a temperature sufficient to cure the silicone resin; a silicone resin film prepared according to the preceding method; and a nanomaterial-tilled silicone composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Application No. 60/752,727,filed Dec. 21, 2005.

FIELD OF THE INVENTION

The present invention relates to a method of preparing a silicone resinfilm and more particularly to a method comprising coating a releaseliner with a nanomaterial-filled silicone composition comprising ahydrosilylation-curable silicone composition and a carbon nanomaterial,and heating the coated release liner at a temperature sufficient to curethe silicone resin. The present invention also relates to a siliconeresin film prepared according to the preceding method, and to ananomaterial-filled silicone composition.

BACKGROUND OF THE INVENTION

Silicone resins are useful in a variety of applications by virtue oftheir unique combination of properties, including high thermalstability, good moisture resistance, excellent flexibility, high oxygenresistance, low dielectric constant, and high transparency. For example,silicone resins are widely used as protective or dielectric coatings inthe automotive, electronic, construction, appliance, and aerospaceindustries.

Although silicone resin coatings can be used to protect, insulate, orbond a variety of substrates, free standing silicone resin films havelimited utility due to low tear strength, high brittleness, low glasstransition temperature, and high coefficient of thermal expansion.Consequently, there is a need for free standing silicone resin filmshaving improved mechanical and thermal properties.

SUMMARY OF THE INVENTION

The present invention is directed to a method of preparing a siliconeresin film, the method comprising the steps of:

coating a release liner with a nanomaterial-filled silicone composition,wherein the silicone composition comprises:

-   -   a hydrosilylation-curable silicone composition comprising a        silicone resin having an average of at least two silicon-bonded        alkenyl groups or silicon-bonded hydrogen atoms per molecule,        and    -   a carbon nanomaterial; and

heating the coated release liner at a temperature sufficient to cure thesilicone resin.

The present invention is also directed to a silicone resin film preparedaccording to the aforementioned method.

The present method is further directed to a nanomaterial-filled siliconecomposition, comprising:

a hydrosilylation-curable silicone composition comprising a siliconeresin having an average of at least two silicon-bonded alkenyl groups orsilicon-bonded hydrogen atoms per molecule; and

a carbon nanomaterial.

The silicone resin film of the present invention has low coefficient ofthermal expansion, high tensile strength, and high modulus compared to asilicone resin film prepared from the same silicone composition absentthe carbon nanomaterial. Also, although the filled (i.e., carbonnanomaterial-containing) and unfilled silicone resin films havecomparable glass transition temperatures, the former film exhibits asmaller change in modulus in the temperature range corresponding to theglass transition.

The silicone resin film of the present invention is useful inapplications requiring films having high thermal stability, flexibility,mechanical strength, and transparency. For example, the silicone resinfilm can be used as an integral component of flexible displays, solarcells, flexible electronic boards, touch screens, fire-resistantwallpaper, and impact-resistant windows. The film is also a suitablesubstrate for transparent or nontransparent electrodes.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term “free of aliphatic unsaturation” means thehydrocarbyl or halogen-substituted hydrocarbyl group does not contain analiphatic carbon-carbon double bond or carbon-carbon triple bond. Also,the term “mol % of the groups R² in the silicone resin are alkenyl” isdefined as the ratio of the number of moles of silicon-bonded alkenylgroups in the silicone resin to the total number of moles of the groupsR² in the resin, multiplied by 100. Further, the term “mol % of thegroups R⁴ in the organohydrogenpolysiloxane resin are organosilylalkyl”is defined as the ratio of the number of moles of silicon-bondedorganosilylalkyl groups in the organohydrogenpolysiloxane resin to thetotal number of moles of the groups R⁴ in the resin, multiplied by 100.Still further, the term “mol % of the groups R⁵ in the silicone resinare hydrogen” is defined as the ratio of the number of moles ofsilicon-bonded hydrogen atoms in the silicone resin to the total numberof moles of the groups R⁵ in the resin, multiplied by 100.

A nanomaterial-filled silicone composition according to the presentinvention, comprises:

a hydrosilylation-curable silicone composition comprising a siliconeresin having an average of at least two silicon-bonded alkenyl groups orsilicon-bonded hydrogen atoms per molecule; and

a carbon nanomaterial.

The hydrosilylation-curable silicone composition can be anyhydrosilylation-curable silicone composition containing a silicone resinhaving an average of at least two silicon-bonded alkenyl groups orsilicon-bonded hydrogen atoms per molecule. Typically, thehydrosilylation-curable silicone composition comprises theaforementioned silicone resin; an organosilicon compound in an amountsufficient to cure the silicone resin, wherein the organosiliconcompound has an average of at least two silicon-bonded hydrogen atoms orsilicon-bonded alkenyl groups per molecule capable of reacting with thesilicon-bonded alkenyl groups or silicon-bonded hydrogen atoms in thesilicone resin; and a catalytic amount of a hydrosilylation catalyst.

The silicone resin of the hydrosilylation-curable silicone compositionis typically a copolymer containing T and/or Q siloxane units incombination with M and/or D siloxane units. Moreover, the silicone resincan be a rubber-modified silicone resin, described below for the fifthand sixth embodiments of the hydrosilylation-curable siliconecomposition.

According to a first embodiment, the hydrosilylation-curable siliconecomposition comprises (A) a silicone resin having the formula (R¹R²₂SiO_(1/2))_(w)(R² ₂SiO_(2/2))_(x) (R¹SiO_(3/2))_(y)(SiO_(4/2))_(z)(I),wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀ halogen-substitutedhydrocarbyl, both free of aliphatic unsaturation, R² is R¹ or alkenyl, wis from 0 to 0.8, x is from 0 to 0.6, y is from 0 to 0.99, z is from 0to 0.35, w+x+y+z=1, y+z/(w+x+y+z) is from 0.2 to 0.99, and w+x/(w+x+y+z)is from 0.01 to 0.8, provided the silicone resin has an average of atleast two silicon-bonded alkenyl groups per molecule; (B) anorganosilicon compound having an average of at least two silicon-bondedhydrogen atoms per molecule in an amount sufficient to cure the siliconeresin; and (C) a catalytic amount of a hydrosilylation catalyst.

Component (A) is at least one silicone resin having the formula (R¹R²₂SiO_(1/2))_(w)(R² ₂SiO_(2/2))_(x)(R¹SiO_(3/2))_(y)(SiO_(4/2))_(z) (I),wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀ halogen-substitutedhydrocarbyl, both free of aliphatic unsaturation, R² is R¹ or alkenyl, wis from 0 to 0.8, x is from 0 to 0.6, y is from 0 to 0.99, z is from 0to 0.35, w+x+y+z=1, y+z/(w+x+y+z) is from 0.2 to 0.99, and w+x/(w+x+y+z)is from 0.01 to 0.8, provided the silicone resin has an average of atleast two silicon-bonded alkenyl groups per molecule.

The hydrocarbyl and halogen-substituted hydrocarbyl groups representedby R¹ are free of aliphatic unsaturation and typically have from 1 to 10carbon atoms, alternatively from 1 to 6 carbon atoms. Acyclichydrocarbyl and halogen-substituted hydrocarbyl groups containing atleast 3 carbon atoms can have a branched or unbranched structure.Examples of hydrocarbyl groups represented by R¹ include, but are notlimited to, alkyl, such as methyl, ethyl, propyl, 1-methylethyl, butyl,1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, pentyl,1-methylbutyl, 1-ethylpropyl, 2-methylbutyl, 3-methylbutyl,1,2-dimethylpropyl, 2,2-dimethylpropyl, hexyl, heptyl, octyl, nonyl, anddecyl; cycloalkyl, such as cyclopentyl, cyclohexyl, andmethylcyclohexyl; aryl, such as phenyl and naphthyl; alkaryl, such astolyl and xylyl; and aralkyl, such as benzyl and phenethyl. Examples ofhalogen-substituted hydrocarbyl groups represented by R¹ include, butare not limited to, 3,3,3-trifluoropropyl, 3-chloropropyl, chlorophenyl,dichlorophenyl, 2,2,2-trifluoroethyl, 2,2,3,3-tetrafluoropropyl, and2,2,3,3,4,4,5,5-octafluoropentyl.

The alkenyl groups represented by R², which may be the same ordifferent, typically have from 2 to about 10 carbon atoms, alternativelyfrom 2 to 6 carbon atoms, and are exemplified by, but not limited to,vinyl, allyl, butenyl, hexenyl, and octenyl.

In the formula (I) of the silicone resin, the subscripts w, x, y, and zare mole fractions. The subscript w typically has a value of from 0 to0.8, alternatively from 0.02 to 0.75, alternatively from 0.05 to 0.3;the subscript x typically has a value of from 0 to 0.6, alternativelyfrom 0 to 0.45, alternatively from 0 to 0.25; the subscript y typicallyhas a value of from 0 to 0.99, alternatively from 0.25 to 0.8,alternatively from 0.5 to 0.8; the subscript z typically has a value offrom 0 to 0.35, alternatively from 0 to 0.25, alternatively from 0 to0.15. Also, the ratio y+z/(w+x+y+z) is typically from 0.2 to 0.99,alternatively from 0.5 to 0.95, alternatively from 0.65 to 0.9. Further,the ratio w+x/(w+x+y+z) is typically from 0.01 to 0.80, alternativelyfrom 0.05 to 0.5, alternatively from 0.1 to 0.35.

Typically at least 50 mol %, alternatively at least 65 mol %,alternatively at least 80 mol % of the groups R² in the silicone resinare alkenyl.

The silicone resin typically has a number-average molecular weight(M_(n)) of from 500 to 50,000, alternatively from 500 to 10,000,alternatively 1,000 to 3,000, where the molecular weight is determinedby gel permeation chromatography employing a low angle laser lightscattering detector, or a refractive index detector and silicone resin(MQ) standards.

The viscosity of the silicone resin at 25° C. is typically from 0.01 to100,000 Pa·s, alternatively from 0.1 to 10,000 Pa·s, alternatively from1 to 100 Pa·s.

The silicone resin typically contains less than 10% (w/w), alternativelyless than 5% (w/w), alternatively less than 2% (w/w), of silicon-bondedhydroxy groups, as determined by ²⁹Si NMR.

The silicone resin contains R¹SiO_(3/2) units (i.e., T units) and/orSiO_(4/2) units (i.e., Q units) in combination with R¹R² ₂SiO_(1/2)units (i.e., M units) and/or R² ₂SiO_(2/2) units (i.e., D units), whereR¹ and R² are as described and exemplified above. For example, thesilicone resin can be a DT resin, an MT resin, an MDT resin, a DTQresin, and MTQ resin, and MDTQ resin, a DQ resin, an MQ resin, a DTQresin, an MTQ resin, or an MDQ resin.

Examples of silicone resins include, but are not limited to, resinshaving the following formulae:

(Vi₂MeSiO_(1/2))_(0.25)(PhSiO_(3/2))_(0.75),(ViMe₂SiO_(1/2))_(0.25)(PhSiO_(3/2))_(0.75),

(ViMe₂SiO_(1/2))_(0.25)(MeSiO_(3/2))_(0.25)(PhSiO_(3/2))_(0.50),(ViMe₂SiO_(1/2))_(0.15)(PhSiO_(3/2))_(0.75)(SiO_(4/2))_(0.1), and(Vi₂MeSiO_(1/2))_(0.15)(ViMe₂SiO_(1/2))_(0.1)(PhSiO_(3/2))_(0.75), whereMe is methyl, Vi is vinyl, Ph is phenyl, and the numerical subscriptsoutside the parenthesis denote mole fractions. Also, in the precedingformulae, the sequence of units is unspecified.

Component (A) can be a single silicone resin or a mixture comprising twoor more different silicone resins, each as described above.

Methods of preparing silicone resins are well known in the art; many ofthese resins are commercially available: Silicone resins are typicallyprepared by cohydrolyzing the appropriate mixture of chlorosilaneprecursors in an organic solvent, such as toluene. For example, asilicone resin consisting essentially of R¹R² ₂SiO_(1/2) units andR¹SiO_(3/2) units can be prepared by cohydrolyzing a compound having theformula R¹R² ₂SiCl and a compound having the formula R¹SiCl₃ in toluene,where R¹ and R² are as defined and exemplified above. The aqueoushydrochloric acid and silicone hydrolyzate are separated and thehydrolyzate is washed with water to remove residual acid and heated inthe presence of a mild condensation catalyst to “body” the resin to therequisite viscosity. If desired, the resin can be further treated with acondensation catalyst in an organic solvent to reduce the content ofsilicon-bonded hydroxy groups. Alternatively, silanes containinghydrolysable groups other than chloro, such —Br, —I, —OCH₃, —OC(O)CH₃,—N(CH₃)₂, NHCOCH₃, and —SCH₃, can be utilized as starting materials inthe cohydrolysis reaction. The properties of the resin products dependon the types of silanes, the mole ratio of silanes, the degree ofcondensation, and the processing conditions.

Component (B) is at least one organosilicon compound having an averageof at least two silicon-bonded hydrogen atoms per molecule in an amountsufficient to cure the silicone resin of component (A).

The organosilicon compound has an average of at least two silicon-bondedhydrogen atoms per molecule, alternatively at least three silicon-bondedhydrogen atoms per molecule. It is generally understood thatcross-linking occurs when the sum of the average number of alkenylgroups per molecule in component (A) and the average number ofsilicon-bonded hydrogen atoms per molecule in component (B) is greaterthan four.

The organosilicon compound can be an organohydrogensilane or anorganohydrogensiloxane. The organohydrogensilane can be a monosilane,disilane, trisilane, or polysilane. Similarly, theorganohydrogensiloxane can be a disiloxane, trisiloxane, orpolysiloxane. The structure of the organosilicon compound can be linear,branched, cyclic, or resinous. Cyclosilanes and cyclosiloxanes typicallyhave from 3 to 12 silicon atoms, alternatively from 3 to 10 siliconatoms, alternatively from 3 to 4 silicon atoms. In acyclic polysilanesand polysiloxanes, the silicon-bonded hydrogen atoms can be located atterminal, pendant, or at both terminal and pendant positions.

Examples of organohydrogensilanes include, but are not limited to,diphenylsilane, 2-chloroethylsilane, bis[(p-dimethylsilyl)phenyl]ether,1,4-dimethyldisilylethane, 1,3,5-tris(dimethylsilyl)benzene,1,3,5-trimethyl-1,3,5-trisilane, poly(methylsilylene)phenylene, andpoly(methylsilylene)methylene.

The organohydrogensilane can also have the formula HR¹ ₂Si—R³—SiR¹ ₂H,wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀ halogen-substitutedhydrocarbyl, both free of aliphatic unsaturation, and R³ is ahydrocarbylene group free of aliphatic unsaturation having a formulaselected from:

wherein g is from 1 to 6. The hydrocarbyl and halogen-substitutedhydrocarbyl groups represented by R¹ are as defined and exemplifiedabove for the silicone resin of component (A).

Examples of organohydrogensilanes having the formula HR¹ ₂Si—R³—SiR¹ ₂H,wherein R¹ and R³ are as described and exemplified above include, butare not limited to, silanes having the following formulae:

Examples of organohydrogensiloxanes include, but are not limited to,1,1,3,3-tetramethyldisiloxane, 1,1,3,3-tetraphenyldisiloxane,phenyltris(dimethylsiloxy)silane, 1,3,5-trimethylcyclotrisiloxane, atrimethylsiloxy-terminated poly(methylhydrogensiloxane), atrimethylsiloxy-terminatedpoly(dimethylsiloxane/methylhydrogensiloxane), adimethylhydrogensiloxy-terminated poly(methylhydrogensiloxane), and aresin consisting essentially of HMe₂SiO_(1/2) units, Me₃SiO_(1/2) units,and SiO_(4/2) units, wherein Me is methyl.

The organohydrogensiloxane can also be an organohydrogenpolysiloxaneresin having the formula (R¹R⁴ ₂SiO_(2/2))_(w)(R⁴₂SiO_(2/2))_(x)(R¹SiO_(3/2))_(y)(SiO_(4/2))_(z) (II), wherein R¹ is C₁to C₁₀ hydrocarbyl or C₁ to C₁₀ halogen-substituted hydrocarbyl, bothfree of aliphatic unsaturation, R⁴ is R¹ or an organosilylalkyl grouphaving at least one silicon-bonded hydrogen atom, w is from 0 to 0.8, xis from 0 to 0.6, y is from 0 to 0.99, z is from 0 to 0.35, w+x+y+z=1,y+z/(w+x+y+z) is from 0.2 to 0.99, and w+x/(w+x+y+z) is from 0.01 to0.8, provided at least 50 mol % of the groups R⁴ are organosilylalkyl.

The hydrocarbyl and halogen-substituted hydrocarbyl groups representedby R¹ are as described and exemplified above for the silicone resin ofcomponent (A). Examples of organosilylalkyl groups represented by R⁴include, but are not limited to, groups having the following formulae:

—CH₂CH₂SiMe₂H, —CH₂CH₂SiMe₂C_(n)H_(2n)SiMe₂H,—CH₂CH₂SiMe₂C_(n)H_(2n)SiMePhH, —CH₂CH₂SiMePhH, —CH₂CH₂SiPh₂H,—CH₂CH₂SiMePhC_(n)H_(2n)SiPh₂H, —CH₂CH₂SiMePhC_(n)H_(2n)SiMe₂H,—CH₂CH₂SiMePhOSiMePhH, and

—CH₂CH₂SiMePhOSiPh(OSiMePhH)₂, where Me is methyl, Ph is phenyl, and thesubscript n has a value of from 2 to 10.

In the formula (II) of the organohydrogenpolysiloxane resin, thesubscripts w, x, y, and z are mole fractions. The subscript w typicallyhas a value of from 0 to 0.8, alternatively from 0.02 to 0.75,alternatively from 0.05 to 0.3; the subscript x typically has a value offrom 0 to 0.6, alternatively from 0 to 0.45, alternatively from 0 to0.25; the subscript y typically has a value of from 0 to 0.99,alternatively from 0.25 to 0.8, alternatively from 0.5 to 0.8; thesubscript z typically has a value of from 0 to 0.35, alternatively from0 to 0.25, alternatively from 0 to 0.15. Also, the ratio y+z/(w+x+y+z)is typically from 0.2 to 0.99, alternatively from 0.5 to 0.95,alternatively from 0.65 to 0.9. Further, the ratio w+x/(w+x+y+z) istypically from 0.01 to 0.80, alternatively from 0.05 to 0.5,alternatively from 0.1 to 0.35.

Typically, at least 50 mol %, alternatively at least 65 mol %,alternatively at least 80 mol % of the groups R⁴ in theorganohydrogenpolysiloxane resin are organosilylalkyl groups having atleast one silicon-bonded hydrogen atom.

The organohydrogenpolysiloxane resin typically has a number-averagemolecular weight (M_(n)) of from 500 to 50,000, alternatively from 500to 10,000, alternatively 1,000 to 3,000, where the molecular weight isdetermined by gel permeation chromatography employing a low angle laserlight scattering detector, or a refractive index detector and siliconeresin (MQ) standards.

The organohydrogenpolysiloxane resin typically contains less than 10%(w/w), alternatively less than 5% (w/w), alternatively less than 2%(w/w), of silicon-bonded hydroxy groups, as determined by ²⁹Si NMR.

The organohydrogenpolysiloxane resin contains R¹SiO_(3/2) units (i.e., Tunits) and/or SiO_(4/2) units (i.e., Q units) in combination with R¹R⁴₂SiO_(1/2) units (i.e., M units) and/or R⁴ ₂SiO_(2/2) units (i.e., Dunits), where R¹ and R⁴ are as described and exemplified above. Forexample, the organohydrogenpolysiloxane resin can be a DT resin, an MTresin, an MDT resin, a DTQ resin, and MTQ resin, and MDTQ resin, a DQresin, an MQ resin, a DTQ resin, an MTQ resin, or an MDQ resin.

Examples of organohydrogenpolysiloxane resins include, but are notlimited to, resins having the following formulae:

((HMe₂SiC₆H₄SiMe₂CH₂CH₂)₂MeSiO_(1/2))_(0.12)(PhSiO_(3/2))_(0.88),((HMe₂SiC₆H₄SiMe₂CH₂CH₂)₂MeSiO_(1/2))_(0.17)(PhSiO_(3/2))_(0.83),

((HMe₂SiC₆H₄SiMe₂CH₂CH₂)₂MeSiO_(1/2))_(0.17)(MeSiO_(3/2))_(0.17)(PhSiO_(3/2))_(0.66),((HMe₂SiC₆H₄SiMe₂CH₂CH₂)₂MeSiO_(1/2))_(0.15)(PhSiO_(3/2))_(0.75)(SiO_(4/2))_(0.10),and((HMe₂SiC₆H₄SiMe₂CH₂CH₂)₂MeSiO_(1/2))_(0.08)((HMe₂SiC₆H₄SiMe₂CH₂CH₂)Me₂SiO_(1/2))_(0.06)(PhSiO_(3/2))_(0.86), where Me is methyl, Ph isphenyl, C₆H₄ denotes a para-phenylene group, and the numericalsubscripts outside the parenthesis denote mole fractions. Also, in thepreceding formulae, the sequence of units is unspecified.

Component (B) can be a single organosilicon compound or a mixturecomprising two or more different organosilicon compounds, each asdescribed above. For example, component (B) can be a singleorganohydrogensilane, a mixture of two different organohydrogensilanes,a single organohydrogensiloxane, a mixture of two differentorganohydrogensiloxanes, or a mixture of an organohydrogensilane and anorganohydrogensiloxane. In particular, component (B) can be a mixturecomprising at least 0.5% (w/w), alternatively at least 50% (w/w),alternatively at least 75% (w/w), based on the total weight of component(B), of the organohydrogenpolysiloxane resin having the formula (II),and an organohydrogensilane and/or organohydrogensiloxane, the latterdifferent from the organohydrogenpolysiloxane resin.

The concentration of component (B) is sufficient to cure (cross-link)the silicone resin of component (A). The exact amount of component (B)depends on the desired extent of cure, which generally increases as theratio of the number of moles of silicon-bonded hydrogen atoms incomponent (B) to the number of moles of alkenyl groups in component (A)increases. The concentration of component (B) is typically sufficient toprovide from 0.4 to 2 moles of silicon-bonded hydrogen atoms,alternatively from 0.8 to 1.5 moles of silicon-bonded hydrogen atoms,alternatively from 0.9 to 1.1 moles of silicon-bonded hydrogen atoms,per mole of alkenyl groups in component (A).

Methods of preparing organosilicon compounds containing silicon-bondedhydrogen atoms are well known in the art. For example,organohydrogensilanes can be prepared by reaction of Grignard reagentswith alkyl or aryl halides. In particular, organohydrogensilanes havingthe formula HR¹ ₂Si—R³—SiR¹ ₂H can be prepared by treating an aryldihalide having the formula R³X₂ with magnesium in ether to produce thecorresponding Grignard reagent and then treating the Grignard reagentwith a chlorosilane having the formula HR¹ ₂SiCl, where R¹ and R³ are asdescribed and exemplified above.

Methods of preparing organohydrogensiloxanes, such as the hydrolysis andcondensation of organohalosilanes, are also well known in the art.

In addition, the organohydrogenpolysiloxane resin having the formula(II) can be prepared by reacting (a) a silicone resin having the formula(R¹R² ₂SiO_(1/2))_(w)(R² ₂SiO_(2/2))_(x)(R¹SiO_(3/2))_(y)(SiO_(4/2))_(z) (I) with (b) an organosilicon compoundhaving an average of from two to four silicon-bonded hydrogen atoms permolecule and a molecular weight less than 1,000, in the presence of (c)a hydrosilylation catalyst and, optionally, (d) an organic solvent,wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀ halogen-substitutedhydrocarbyl, both free of aliphatic unsaturation, R² is R¹ or alkenyl, wis from 0 to 0.8, x is from 0 to 0.6, y is from 0 to 0.99, z is from 0to 0.35, w+x+y+z=1, y+z/(w+x+y+z) is from 0.2 to 0.99, and w+x/(w+x+y+z)is from 0.01 to 0.8, provided the silicone resin (a) has an average ofat least two silicon-bonded alkenyl groups per molecule, and the moleratio of silicon-bonded hydrogen atoms in (b) to alkenyl groups in (a)is from 1.5 to 5.

Silicone resin (a) is as described and exemplified above for component(A) of the silicone composition. Silicone resin (a) can be the same asor different than the silicone resin used as component (A) in thehydrosilylation-curable silicone composition.

Organosilicon compound (b) is at least one organosilicon compound havingan average of from two to four silicon-bonded hydrogen atoms permolecule. Alternatively, the organosilicon compound has an average offrom two to three silicon-bonded hydrogen atoms per molecule. Theorganosilicon compound typically has a molecular weight less than 1,000,alternatively less than 750, alternatively less than 500. Thesilicon-bonded organic groups in the organosilicon compound are selectedfrom hydrocarbyl and halogen-substituted hydrocarbyl groups, both freeof aliphatic unsaturation, which are as described and exemplified abovefor R¹ in the formula of the silicone resin of component (A).

Organosilicon compound (b) can be an organohydrogensilane or anorganohydrogensiloxane. The organohydrogensilane can be a monosilane,disilane, trisilane, or polysilane. Similarly, theorganohydrogensiloxane can be a disiloxane, trisiloxane, orpolysiloxane. The structure of the organosilicon compound can be linear,branched, or cyclic. Cyclosilanes and cyclosiloxanes typically have from3 to 12 silicon atoms, alternatively from 3 to 10 silicon atoms,alternatively from 3 to 4 silicon atoms. In acyclic polysilanes andpolysiloxanes, the silicon-bonded hydrogen atoms can be located atterminal, pendant, or at both terminal and pendant positions.

Examples of organohydrogensilanes include, but are not limited to,diphenylsilane, 2-chloroethylsilane, bis[(p-dimethylsilyl)phenyl]ether,1,4-dimethyldisilylethane, 1,3,5-tris(dimethylsilyl)benzene, and1,3,5-trimethyl-1,3,5-trisilane. The organohydrogensilane can also havethe formula HR¹ ₂Si—R³—SiR¹ ₂H, wherein R¹ and R³ are as described andexemplified above.

Examples of organohydrogensiloxanes include, but are not limited to,1,1,3,3-tetramethyldisiloxane, 1,1,3,3-tetraphenyldisiloxane,phenyltris(dimethylsiloxy)silane, and 1,3,5-trimethylcyclotrisiloxane.

Organosilicon compound (b) can be a single organosilicon compound or amixture comprising two or more different organosilicon compounds, eachas described above. For example, component (B) can be a singleorganohydrogensilane, a mixture of two different organohydrogensilanes,a single organohydrogensiloxane, a mixture of two differentorganohydrogensiloxanes, or a mixture of an organohydrogensilane and anorganohydrogensiloxane.

Methods of preparing organohydrogensilanes, such as the reaction ofGrignard reagents with alkyl or aryl halides, described above, are wellknown in the art. Similarly, methods of preparingorganohydrogensiloxanes, such as the hydrolysis and condensation oforganohalosilanes, are well known in the art.

Hydrosilylation catalyst (c) can be any of the well-knownhydrosilylation catalysts comprising a platinum group metal (i.e.,platinum, rhodium, ruthenium, palladium, osmium and iridium) or acompound containing a platinum group metal. Preferably, the platinumgroup metal is platinum, based on its high activity in hydrosilylationreactions.

Hydrosilylation catalysts include the complexes of chloroplatinic acidand certain vinyl-containing organosiloxanes disclosed by Willing inU.S. Pat. No. 3,419,593, which is hereby incorporated by reference. Acatalyst of this type is the reaction product of chloroplatinic acid and1,3-diethenyl-1,1,3,3-tetramethyldisiloxane.

The hydrosilylation catalyst can also be a supported hydrosilylationcatalyst comprising a solid support having a platinum group metal on thesurface thereof. A supported catalyst can be conveniently separated fromthe organohydrogenpolysiloxane resin product, for example, by filteringthe reaction mixture. Examples of supported catalysts include, but arenot limited to, platinum on carbon, palladium on carbon, ruthenium oncarbon, rhodium on carbon, platinum on silica, palladium on silica,platinum on alumina, palladium on alumina, and ruthenium on alumina.

Organic solvent (d) is at least one organic solvent. The organic solventcan be any aprotic or dipolar aprotic organic solvent that does notreact with silicone resin (a), organosilicon compound (b), or theorganohydrogenpolysiloxane resin under the conditions of the presentmethod, and is miscible with components (a), (b), and theorganohydrogenpolysiloxane resin.

Examples of organic solvents include, but are not limited to, saturatedaliphatic hydrocarbons such as n-pentane, hexane, n-heptane, isooctaneand dodecane; cycloaliphatic hydrocarbons such as cyclopentane andcyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene andmesitylene; cyclic ethers such as tetrahydrofuran (THF) and dioxane;ketones such as methyl isobutyl ketone (MIBK); halogenated alkanes suchas trichloroethane; and halogenated aromatic hydrocarbons such asbromobenzene and chlorobenzene. Organic solvent (d) can be a singleorganic solvent or a mixture comprising two or more different organicsolvents, each as described above.

The reaction can be carried out in any standard reactor suitable forhydrosilylation reactions. Suitable reactors include glass andTeflon-lined glass reactors. Preferably, the reactor is equipped with ameans of agitation, such as stirring. Also, preferably, the reaction iscarried out in an inert atmosphere, such as nitrogen or argon, in theabsence of moisture.

The silicone resin, organosilicon compound, hydrosilylation catalyst,and, optionally, organic solvent, can be combined in any order.Typically, organosilicon compound (b) and hydrosilylation catalyst (c)are combined before the introduction of the silicone resin (a) and,optionally, organic solvent (d).

The reaction is typically carried out at a temperature of from 0 to 150°C., alternatively from room temperature (˜23±2° C.) to 115° C. When thetemperature is less than 0° C., the rate of reaction is typically veryslow.

The reaction time depends on several factors, such as the structures ofthe silicone resin and the organosilicon compound, and the temperature.The time of reaction is typically from 1 to 24 h at a temperature offrom room temperature (˜23±2° C.) to 150° C. The optimum reaction timecan be determined by routine experimentation using the methods set forthin the Examples section below.

The mole ratio of silicon-bonded hydrogen atoms in organosiliconcompound (b) to alkenyl groups in silicone resin (a) is typically from1.5 to 5, alternatively from 1.75 to 3, alternatively from 2 to 2.5.

The concentration of hydrosilylation catalyst (c) is sufficient tocatalyze the addition reaction of silicone resin (a) with organosiliconcompound (b). Typically, the concentration of hydrosilylation catalyst(c) is sufficient to provide from 0.1 to 1000 ppm of a platinum groupmetal, alternatively from 1 to 500 ppm of a platinum group metal,alternatively from 5 to 150 ppm of a platinum group metal, based on thecombined weight of silicone resin (a) and organosilicon compound (b).The rate of reaction is very slow below 0.1 ppm of platinum group metal.The use of more than 1000 ppm of platinum group metal results in noappreciable increase in reaction rate, and is therefore uneconomical.

The concentration of organic solvent (d) is typically from 0 to 99%(w/w), alternatively from 30 to 80% (w/w), alternatively from 45 to 60%(w/w), based on the total weight of the reaction mixture.

The organohydrogenpolysiloxane resin can be used without isolation orpurification in the first embodiment of the hydrosilylation-curablesilicone composition or the resin can be separated from most of thesolvent by conventional methods of evaporation. For example, thereaction mixture can be heated under reduced pressure. Moreover, whenthe hydrosilylation catalyst used to prepare theorganohydrogenpolysiloxane resin is a supported catalyst, describedabove, the resin can be readily separated from the hydrosilylationcatalyst by filtering the reaction mixture. However, when theorganohydrogenpolysiloxane resin is not separated from thehydrosilylation catalyst used to prepare the resin, the catalyst may beused as component (C) of the first embodiment of thehydrosilylation-curable silicone composition.

Component (C) of the hydrosilylation-curable silicone composition is atleast one hydrosilylation catalyst that promotes the addition reactionof component (A) with component (B). The hydrosilylation catalyst can beany of the well-known hydrosilylation catalysts comprising a platinumgroup metal, a compound containing a platinum group metal, or amicroencapsulated platinum group metal-containing catalyst. Platinumgroup metals include platinum, rhodium, ruthenium, palladium, osmium andiridium. Preferably, the platinum group metal is platinum, based on itshigh activity in hydrosilylation reactions.

Preferred hydrosilylation catalysts include the complexes ofchloroplatinic acid and certain vinyl-containing organosiloxanesdisclosed by Willing in U.S. Pat. No. 3,419,593, which is herebyincorporated by reference. A preferred catalyst of this type is thereaction product of chloroplatinic acid and1,3-diethenyl-1,1,3,3-tetramethyldisiloxane.

The hydrosilylation catalyst can also be a microencapsulated platinumgroup metal-containing catalyst comprising a platinum group metalencapsulated in a thermoplastic resin. Compositions containingmicroencapsulated hydrosilylation catalysts are stable for extendedperiods of time, typically several months or longer, under ambientconditions, yet cure relatively rapidly at temperatures above themelting or softening point of the thermoplastic resin(s).Microencapsulated hydrosilylation catalysts and methods of preparingthem are well known in the art, as exemplified in U.S. Pat. No.4,766,176 and the references cited therein; and U.S. Pat. No. 5,017,654.

Component (C) can be a single hydrosilylation catalyst or a mixturecomprising two or more different catalysts that differ in at least oneproperty, such as structure, form, platinum group metal, complexingligand, and thermoplastic resin.

The concentration of component (C) is sufficient to catalyze theaddition reaction of component (A) with component (B). Typically, theconcentration of component (C) is sufficient to provide from 0.1 to 1000ppm of a platinum group metal, preferably from 1 to 500 ppm of aplatinum group metal, and more preferably from 5 to 150 ppm of aplatinum group metal, based on the combined weight of components (A) and(B). The rate of cure is very slow below 0.1 ppm of platinum groupmetal. The use of more than 1000 ppm of platinum group metal results inno appreciable increase in cure rate, and is therefore uneconomical.

According to a second embodiment, the hydrosilylation-curable siliconecomposition comprises (A′) a silicone resin having the formula (R¹R⁵₂SiO_(1/2))_(w)(R⁵ ₂SiO_(2/2))_(x)(R⁵SiO_(3/2))_(y)(SiO_(4/2))_(z)(III), wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀halogen-substituted hydrocarbyl, both free of aliphatic unsaturation, R⁵is R¹ or H, w is from 0 to 0.8, x is from 0 to 0.6, y is from 0 to 0.99,z is from 0 to 0.35, w+x+y+z=1, y+z/(w+x+y+z) is from 0.2 to 0.99, andw+x/(w+x+y+z) is from 0.01 to 0.8, provided the silicone resin has anaverage of at least two silicon-bonded hydrogen atoms per molecule; (B′)an organosilicon compound having an average of at least twosilicon-bonded alkenyl groups per molecule in an amount sufficient tocure the silicone resin; and (C) a catalytic amount of a hydrosilylationcatalyst.

Component (A′) is at least one silicone resin having the formula (R¹R⁵₂SiO_(1/2))_(w)(R⁵ ₂SiO_(2/2))_(x)(R⁵ SiO_(3/2))_(y)(SiO_(4/2))_(z)(III), wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀halogen-substituted hydrocarbyl, both free of aliphatic unsaturation, R⁵is R¹ or —H, w is from 0 to 0.8, x is from 0 to 0.6, y is from 0 to0.99, z is from 0 to 0.35, w+x+y+z=1, y+z/(w+x+y+z) is from 0.2 to 0.99,and w+x/(w+x+y+z) is from 0.01 to 0.8, provided the silicone resin hasan average of at least two silicon-bonded hydrogen atoms per molecule.In the formula (III), R¹, w, x, y, z, y+z/(w+x+y+z), and w+x/(w+x+y+z)are as described and exemplified above for the silicone resin having theformula (I).

Typically at least 50 mol %, alternatively at least 65 mol %,alternatively at least 80 mol % of the groups R⁵ in the silicone resinare hydrogen.

The silicone resin typically has a number-average molecular weight(M_(n)) of from 500 to 50,000, alternatively from 500 to 10,000,alternatively 1,000 to 3,000, where the molecular weight is determinedby gel permeation chromatography employing a low angle laser lightscattering detector, or a refractive index detector and silicone resin(MQ) standards.

The viscosity of the silicone resin at 25° C. is typically from 0.01 to100,000 Pa·s, alternatively from 0.1 to 10,000 Pa·s, alternatively from1 to 100 Pa·s.

The silicone resin typically contains less than 10% (w/w), alternativelyless than 5% (w/w), alternatively less than 2% (w/w), of silicon-bondedhydroxy groups, as determined by ²⁹Si NMR.

The silicone resin contains R⁵SiO_(3/2) units (i.e., T units) and/orSiO_(4/2) units (i.e., Q units) in combination with R¹R⁵ ₂SiO_(1/2)units (i.e., M units) and/or R⁵ ₂SiO_(2/2) units (i.e., D units). Forexample, the silicone resin can be a DT resin, an MT resin, an MDTresin, a DTQ resin, and MTQ resin, and MDTQ resin, a DQ resin, an MQresin, a DTQ resin, an MTQ resin, or an MDQ resin.

Examples of silicone resins suitable for use as component (A′) include,but are not limited to, resins having the following formulae:

(HMe₂SiO_(1/2))_(0.25)(PhSiO_(3/2))_(0.75),(HMeSiO_(2/2))_(0.3)(PhSiO_(3/2))_(0.6)(MeSiO_(3/2))_(0.1), and

(Me₃SiO_(1/2))_(0.1)(H₂SiO_(2/2))_(0.1)(MeSiO_(3/2))_(0.4)(PhSiO_(3/2))_(0.4), where Me is methyl, Ph isphenyl, and the numerical subscripts outside the parenthesis denote molefractions. Also, in the preceding formulae, the sequence of units isunspecified.

Component (A′) can be a single silicone resin or a mixture comprisingtwo or more different silicone resins, each as described above.

Methods of preparing silicone resins containing silicon-bonded hydrogenatoms are well known in the art; many of these resins are commerciallyavailable. Silicone resins are typically prepared by cohydrolyzing theappropriate mixture of chlorosilane precursors in an organic solvent,such as toluene. For example, a silicone resin consisting essentially ofR¹R⁵ ₂SiO_(1/2) units and R⁵SiO_(3/2) units can be prepared bycohydrolyzing a compound having the formula R¹R⁵ ₂SiCl and a compoundhaving the formula R⁵SiCl₃ in toluene, where R¹ and R⁵ are as describedand exemplified above. The aqueous hydrochloric acid and siliconehydrolyzate are separated and the hydrolyzate is washed with water toremove residual acid and heated in the presence of a mild non-basiccondensation catalyst to “body” the resin to the requisite viscosity. Ifdesired, the resin can be further treated with a non-basic condensationcatalyst in an organic solvent to reduce the content of silicon-bondedhydroxy groups. Alternatively, silanes containing hydrolysable groupsother than chloro, such —Br, —I, —OCH₃, —OC(O)CH₃, —N(CH₃)₂, NHCOCH₃,and —SCH₃, can be utilized as starting materials in the cohydrolysisreaction. The properties of the resin products depend on the types ofsilanes, the mole ratio of silanes, the degree of condensation, and theprocessing conditions.

Component (B′) is at least one organosilicon compound having an averageof at least two silicon-bonded alkenyl groups per molecule in an amountsufficient to cure the silicone resin of component (A′).

The organosilicon compound contains an average of at least twosilicon-bonded alkenyl groups per molecule, alternatively at least threesilicon-bonded alkenyl groups per molecule. It is generally understoodthat cross-linking occurs when the sum of the average number ofsilicon-bonded hydrogen atoms per molecule in component (A′) and theaverage number of silicon-bonded alkenyl groups per molecule incomponent (B′) is greater than four.

The organosilicon compound can be an organosilane or an organosiloxane.The organosilane can be a monosilane, disilane, trisilane, orpolysilane. Similarly, the organosiloxane can be a disiloxane,trisiloxane, or polysiloxane. The structure of the organosiliconcompound can be linear, branched, cyclic, or resinous. Cyclosilanes andcyclosiloxanes typically have from 3 to 12 silicon atoms, alternativelyfrom 3 to 10 silicon atoms, alternatively from 3 to 4 silicon atoms. Inacyclic polysilanes and polysiloxanes, the silicon-bonded alkenyl groupscan be located at terminal, pendant, or at both terminal and pendantpositions.

Examples of organosilanes suitable for use as component (B′) include,but are not limited to, silanes having the following formulae:

Vi₄Si, PhSiVi₃, MeSiVi₃, PhMeSiVi₂, Ph₂SiVi₂, and PhSi(CH₂CH═CH₂)₃,where Me is methyl, Ph is phenyl, and Vi is vinyl.

Examples of organosiloxanes suitable for use as component (B′) include,but are not limited to, siloxanes having the following formulae:

PhSi(OSiMe₂Vi)₃, Si(OSiMe₂Vi)₄, MeSi(OSiMe₂Vi)₃, and Ph₂Si(OSiMe₂Vi)₂,where Me is methyl, Ph is phenyl, and Vi is vinyl.

Component (B′) can be a single organosilicon compound or a mixturecomprising two or more different organosilicon compounds, each asdescribed above. For example component (B′) can be a singleorganosilane, a mixture of two different organosilanes, a singleorganosiloxane, a mixture of two different organosiloxanes, or a mixtureof an organosilane and an organosiloxane.

The concentration of component (B′) is sufficient to cure (cross-link)the silicone resin of component (A′). The exact amount of component (B′)depends on the desired extent of cure, which generally increases as theratio of the number of moles of silicon-bonded alkenyl groups incomponent (B′) to the number of moles of silicon-bonded hydrogen atomsin component (A′) increases. The concentration of component (B′) istypically sufficient to provide from 0.4 to 2 moles of silicon-bondedalkenyl groups, alternatively from 0.8 to 1.5 moles of silicon-bondedalkenyl groups, alternatively from 0.9 to 1.1 moles of silicon-bondedalkenyl groups, per mole of silicon-bonded hydrogen atoms in component(A′).

Methods of preparing organosilanes and organosiloxanes containingsilicon-bonded alkenyl groups are well known in the art; many of thesecompounds are commercially available.

Component (C) of the second embodiment of the silicone composition is asdescribed and exemplified above for component (C) of the firstembodiment.

According to a third embodiment, the hydrosilylation-curable siliconecomposition comprises (Au) a silicone resin having the formula (R¹R²₂SiO_(1/2))_(w)(R² ₂SiO_(2/2))_(x)(R¹SiO_(3/2))_(y)(SiO_(4/2))_(z) (I);(B) an organosilicon compound having an average of at least twosilicon-bonded hydrogen atoms per molecule in an amount sufficient tocure the silicone resin; (C) a catalytic amount of a hydrosilylationcatalyst; and (D) a silicone rubber having a formula selected from (i)R¹R² ₂SiO(R² ₂SiO)_(a)SiR² ₂R¹ (IV) and (ii) R⁵R¹ ₂SiO(R¹R⁵SiO)_(b)SiR¹₂R⁵ (V); wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀halogen-substituted hydrocarbyl, both free of aliphatic unsaturation, R²is R¹ or alkenyl, R⁵ is R¹ or —H, subscripts a and b each have a valueof from 1 to 4, w is from 0 to 0.8, x is from 0 to 0.6, y is from 0 to0.99, z is from 0 to 0.35, w+x+y+z=1, y+z/(w+x+y+z) is from 0.2 to 0.99,and w+x/(w+x+y+z) is from 0.01 to 0.8, provided the silicone resin andthe silicone rubber (D)(i) each have an average of at least twosilicon-bonded alkenyl groups per molecule, the silicone rubber (D)(ii)has an average of at least two silicon-bonded hydrogen atoms permolecule, and the mole ratio of silicon-bonded alkenyl groups orsilicon-bonded hydrogen atoms in the silicone rubber (D) tosilicon-bonded alkenyl groups in the silicone resin (A) is from 0.01 to0.5.

Components (A), (B), and (C) of the third embodiment of the siliconecomposition are as described and exemplified above for the firstembodiment.

The concentration of component (B) is sufficient to cure (cross-link)the silicone resin of component (A). When component (D) is (D)(i), theconcentration of component (B) is such that the ratio of the number ofmoles of silicon-bonded hydrogen atoms in component (B) to the sum ofthe number of moles of silicon-bonded alkenyl groups in component (A)and component (D)(i) is typically from 0.4 to 2, alternatively from 0.8to 1.5, alternatively from 0.9 to 1.1. Furthermore, when component (D)is (D)(ii), the concentration of component (B) is such that the ratio ofthe sum of the number of moles of silicon-bonded hydrogen atoms incomponent (B) and component (D)(ii) to the number of moles ofsilicon-bonded alkenyl groups in component (A) is typically from 0.4 to2, alternatively from 0.8 to 1.5, alternatively from 0.9 to 1.1.

Component (D) is a silicone rubber having a formula selected from (i)R¹R² ₂SiO(R² ₂SiO)_(a)SiR² ₂R¹ (IV) and (ii) R⁵R¹ ₂SiO(R¹R⁵SiO)_(b)SiR¹₂R⁵ (V); wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀halogen-substituted hydrocarbyl, both free of aliphatic unsaturation, R²is R¹ or alkenyl, R⁵ is R¹ or —H, and subscripts a and b each have avalue of from 1 to 4, provided the silicone rubber (D)(i) has an averageof at least two silicon-bonded alkenyl groups per molecule, and thesilicone rubber (D)(ii) has an average of at least two silicon-bondedhydrogen atoms per molecule.

Component (D)(i) is at least one silicone rubber having the formula R¹R²₂SiO(R² ₂SiO)_(a)SiR² ₂R¹ (IV), wherein R¹ and R² are as described andexemplified above and the subscript a has a value of from 1 to 4,provided the silicone rubber (D)(i) has an average of at least twosilicon-bonded alkenyl groups per molecule. Alternatively, the subscripta has a value of from 2 to 4 or from 2 to 3.

Examples of silicone rubbers suitable for use as component (D)(i)include, but are not limited to, silicone rubbers having the followingformulae:

ViMe₂SiO(Me₂SiO)_(a)SiMe₂Vi, ViMe₂SiO(Ph₂SiO)_(a)SiMe₂Vi, andViMe₂SiO(PhMeSiO)_(a)SiMe₂Vi, where Me is methyl, Ph is phenyl, Vi isvinyl, and the subscript a has a value of from 1 to 4.

Component (D)(i) can be a single silicone rubber or a mixture comprisingtwo or more different silicone rubbers, each having the formula (IV).

Component (D)(ii) is at least one silicone rubber having the formulaR⁵R¹ ₂SiO (R¹R⁵SiO)_(b)SiR¹ ₂R⁵ (V); wherein R¹ and R⁵ are as describedand exemplified above, and the subscript b has a value of from 1 to 4,provided the silicone rubber (D)(ii) has an average of at least twosilicon-bonded hydrogen atoms per molecule. Alternatively, the subscriptb has a value of from 2 to 4 or from 2 to 3.

Examples of silicone rubbers suitable for use as component (D)(ii)include, but are not limited to, silicone rubbers having the followingformulae:

HMe₂SiO(Me₂SiO)_(b)SiMe₂H, HMe₂SiO(Ph₂SiO)_(b)SiMe₂H,HMe₂SiO(PhMeSiO)_(b)SiMe₂H, and HMe₂SiO(Ph₂SiO)₂(Me₂SiO)₂SiMe₂H, whereMe is methyl, Ph is phenyl, and the subscript b has a value of from 1 to4.

Component (D)(ii) can be a single silicone rubber or a mixturecomprising two or more different silicone rubbers, each having theformula (V).

The mole ratio of silicon-bonded alkenyl groups or silicon-bondedhydrogen atoms in the silicone rubber (D) to silicon-bonded alkenylgroups in the silicone resin (A) is typically from 0.01 to 0.5,alternatively from 0.05 to 0.4, alternatively from 0.1 to 0.3.

Methods of preparing silicone rubbers containing silicon-bonded alkenylgroups or silicon-bonded hydrogen atoms are well known in the art; manyof these compounds are commercially available.

According to a fourth embodiment, the hydrosilylation-curable siliconecomposition comprises (A′) a silicone resin having the formula (R¹R⁵₂SiO_(1/2))_(w)(R⁵ ₂SiO_(2/2))_(x)(R⁵SiO_(3/2))_(y)(SiO_(4/2))_(z)(III); (B′) an organosilicon compound having an average of at least twosilicon-bonded alkenyl groups per molecule in an amount sufficient tocure the silicone resin; (C) a catalytic amount of a hydrosilylationcatalyst; and (D) a silicone rubber having a formula selected from (i)R¹R² ₂SiO(R² ₂SiO)_(a)SiR² ₂R¹ (IV) and (ii) R⁵R¹ ₂SiO(R¹R⁵SiO)_(b)SiR¹₂R⁵ (V); wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀halogen-substituted hydrocarbyl, both free of aliphatic unsaturation, R²is R¹ or alkenyl, R⁵ is R¹ or —H, subscripts a an b each have a value offrom 1 to 4, w is from 0 to 0.8, x is from 0 to 0.6, y is from 0 to0.99, z is from 0 to 0.35, w+x+y+z=1, y+z/(w+x+y+z) is from 0.2 to 0.99,and w+x/(w+x+y+z) is from 0.01 to 0.8, provided the silicone resin andthe silicone rubber (D)(ii) each have an average of at least twosilicon-bonded hydrogen atoms per molecule, the silicone rubber (D)(i)has an average of at least two silicon-bonded alkenyl groups permolecule, and the mole ratio of silicon-bonded alkenyl groups orsilicon-bonded hydrogen atoms in the silicone rubber (D) tosilicon-bonded hydrogen atoms in the silicone resin (A′) is from 0.01 to0.5.

Components (A′), (B′), and (C) of the fourth embodiment of the siliconecomposition are as described and exemplified above for the secondembodiment, and component (D) of the fourth embodiment is as describedand exemplified above for the third embodiment.

The concentration of component (B′) is sufficient to cure (cross-link)the silicone resin of component (A′). When component (D) is (D)(i), theconcentration of component (B′) is such that the ratio of the sum of thenumber of moles of silicon-bonded alkenyl groups in component (B′) andcomponent (D)(i) to the number of moles of silicon-bonded hydrogen atomsin component (A′) is typically from 0.4 to 2, alternatively from 0.8 to1.5, alternatively from 0.9 to 1.1. Furthermore, when component (D) is(D)(ii), the concentration of component (B′) is such that the ratio ofthe number of moles of silicon-bonded alkenyl groups in component (B′)to the sum of the number of moles of silicon-bonded hydrogen atoms incomponent (A′) and component (D)(ii) is typically from 0.4 to 2,alternatively from 0.8 to 1.5, alternatively from 0.9 to 1.1.

The mole ratio of silicon-bonded alkenyl groups or silicon-bondedhydrogen atoms in the silicone rubber (D) to silicon-bonded hydrogenatoms in the silicone resin (A′) is typically from 0.01 to 0.5,alternatively from 0.05 to 0.4, alternatively from 0.1 to 0.3.

According to a fifth embodiment, the hydrosilylation-curable siliconecomposition comprises (A″) a rubber-modified silicone resin prepared byreacting a silicone resin having the formula (R¹R² ₂SiO_(1/2))_(w)(R²₂SiO_(2/2))_(x)(R¹SiO_(3/2))_(y)(SiO_(4/2))_(z) (I) and a siliconerubber having the formula R⁵R¹ ₂SiO(R¹R⁵SiO)_(c)SiR¹ ₂R⁵ (VI) in thepresence of a hydrosilylation catalyst and, optionally, an organicsolvent to form a soluble reaction product, wherein R¹ is C₁ to C₁₀hydrocarbyl or C₁ to C₁₀ halogen-substituted hydrocarbyl, both free ofaliphatic unsaturation, R² is R¹ or alkenyl, R⁵ is R¹ or —H, c has avalue of from greater than 4 to 1,000, w is from 0 to 0.8, x is from 0to 0.6, y is from 0 to 0.99, z is from 0 to 0.35, w+x+y+z=1,y+z/(w+x+y+z) is from 0.2 to 0.99, and w+x/(w+x+y+z) is from 0.01 to0.8, provided the silicone resin (I) has an average of at least twosilicon-bonded alkenyl groups per molecule, the silicone rubber (VI) hasan average of at least two silicon-bonded hydrogen atoms per molecule,and the mole ratio of silicon-bonded hydrogen atoms in the siliconerubber (VI) to silicon-bonded alkenyl groups in silicone resin (I) isfrom 0.01 to 0.5; (B) an organosilicon compound having an average of atleast two silicon-bonded hydrogen atoms per molecule in an amountsufficient to cure the rubber-modified silicone resin; and (C) acatalytic amount of a hydrosilylation catalyst.

Components (B) and (C) of the fifth embodiment of the siliconecomposition are as described and exemplified above for the firstembodiment.

The concentration of component (B) is sufficient to cure (cross-link)the rubber-modified silicone resin. The concentration of component (B)is such that the ratio of the sum of the number of moles ofsilicon-bonded hydrogen atoms in component (B) and the silicone rubber(VI) to the number of moles of silicon-bonded alkenyl groups in thesilicone resin (I) is typically from 0.4 to 2, alternatively from 0.8 to1.5, alternatively from 0.9 to 1.1.

Component (A″) is a rubber-modified silicone resin prepared by reactingat least one silicone resin having the formula (R¹R² ₂SiO_(1/2))_(w)(R²₂SiO_(2/2))_(x)(R¹SiO_(3/2))_(y)(SiO_(4/2))_(z) (I) and at least onesilicone rubber having the formula R⁵R¹ ₂SiO(R¹R⁵SiO)_(c)SiR¹ ₂R⁵ (VI)in the presence of a hydrosilylation catalyst and, optionally, anorganic solvent to form a soluble reaction product, wherein R¹, R², R⁵,w, x, y, z, y+z/(w+x+y+z), and w+x/(w+x+y+z) are as described andexemplified above, and the subscript c has a value of from greater than4 to 1,000.

The silicone resin having the formula (I) is as described andexemplified above for the first embodiment of the silicone composition.Also, the hydrosilylation catalyst and organic solvent are as describedand exemplified above in the method of preparing theorganohydrogenpolysiloxane resin having the formula (II). As used hereinthe term “soluble reaction product” means when organic solvent ispresent, the product of the reaction for preparing component (A″) ismiscible in the organic solvent and does not form a precipitate orsuspension.

In the formula (VI) of the silicone rubber, R¹ and R⁵ are as describedand exemplified above, and the subscript c typically has a value of fromgreater than 4 to 1,000, alternatively from 10 to 500, alternativelyfrom 10 to 50.

Examples of silicone rubbers having the formula (VI) include, but arenot limited to, silicone rubbers having the following formulae:

HMe₂SiO(Me₂SiO)₅₀SiMe₂H, HMe₂SiO(Me₂SiO)₁₀SiMe₂H,HMe₂SiO(PhMeSiO)₂₅SiMe₂H, and Me₃SiO(MeHSiO)₁₀SiMe₃, wherein Me ismethyl, Ph is phenyl, and the numerical subscripts indicate the numberof each type of siloxane unit.

The silicone rubber having the formula (VI) can be a single siliconerubber or a mixture comprising two or more different silicone rubbers,each having the formula (VI).

Methods of preparing silicone rubbers containing silicon-bonded hydrogenatoms are well known in the art; many of these compounds arecommercially available.

The silicone resin (I), silicone rubber (VI), hydrosilylation catalyst,and organic solvent can be combined in any order. Typically, thesilicone resin, silicone rubber, and organic solvent are combined beforethe introduction of the hydrosilylation catalyst.

The reaction is typically carried out at a temperature of from roomtemperature (˜23±2° C.) to 150° C., alternatively from room temperatureto 100° C.

The reaction time depends on several factors, including the structuresof the silicone resin and the silicone rubber, and the temperature. Thecomponents are typically allowed to react for a period of timesufficient to complete the hydrosilylation reaction. This means thecomponents are typically allowed to react until at least 95 mol %,alternatively at least 98 mol %, alternatively at least 99 mol %, of thesilicon-bonded hydrogen atoms originally present in the silicone rubberhave been consumed in the hydrosilylation reaction, as determined byFTIR spectrometry. The time of reaction is typically from 0.5 to 24 h ata temperature of from room temperature (˜23±2° C.) to 100° C. Theoptimum reaction time can be determined by routine experimentation usingthe methods set forth in the Examples section below.

The mole ratio of silicon-bonded hydrogen atoms in the silicone rubber(VI) to silicon-bonded alkenyl groups in the silicone resin (I) istypically from 0.01 to 0.5, alternatively from 0.05 to 0.4,alternatively from 0.1 to 0.3.

The concentration of the hydrosilylation catalyst is sufficient tocatalyze the addition reaction of the silicone resin (I) with thesilicone rubber (VI). Typically, the concentration of thehydrosilylation catalyst is sufficient to provide from 0.1 to 1000 ppmof a platinum group metal, based on the combined weight of the resin andthe rubber.

The concentration of the organic solvent is typically from 0 to 95%(w/w), alternatively from 10 to 75% (w/w), alternatively from 40 to 60%(w/w), based on the total weight of the reaction mixture.

The rubber-modified silicone resin can be used without isolation orpurification in the fifth embodiment of the hydrosilylation-curablesilicone composition or the resin can be separated from most of thesolvent by conventional methods of evaporation. For example, thereaction mixture can be heated under reduced pressure. Moreover, whenthe hydrosilylation catalyst is a supported catalyst, described above,the rubber-modified silicone resin can be readily separated from thehydrosilylation catalyst by filtering the reaction mixture. However,when the rubber-modified silicone resin is not separated from thehydrosilylation catalyst used to prepare the resin, the catalyst may beused as component (C) of the fifth embodiment of thehydrosilylation-curable silicone composition.

According to a sixth embodiment, the hydrosilylation-curable siliconecomposition comprises (A″′) a rubber-modified silicone resin prepared byreacting a silicone resin having the formula (R¹R⁵ ₂SiO_(1/2))_(w)(R⁵₂SiO_(2/2))_(x)(R⁵SiO_(3/2))_(y)(SiO_(4/2))_(z) (III) and a siliconerubber having the formula R¹R² ₂SiO(R² ₂SiO)_(d)SiR² ₂R¹ (VII) in thepresence of a hydrosilylation catalyst and, optionally, an organicsolvent to form a soluble reaction product, wherein R¹ is C₁ to C₁₀hydrocarbyl or C₁ to C₁₀ halogen-substituted hydrocarbyl, both free ofaliphatic unsaturation, R² is R¹ or alkenyl, R⁵ is R¹ or —H, subscript dhas a value of from greater than 4 to 1,000, w is from 0 to 0.8, x isfrom 0 to 0.6, y is from 0 to 0.99, z is from 0 to 0.35, w+x+y+z=1,y+z/(w+x+y+z) is from 0.2 to 0.99, and w+x/(w+x+y+z) is from 0.01 to0.8, provided the silicone resin (III) has an average of at least twosilicon-bonded hydrogen atoms per molecule, the silicone rubber (VII)has an average of at least two silicon-bonded alkenyl groups permolecule, and the mole ratio of silicon-bonded alkenyl groups in thesilicone rubber (VII) to silicon-bonded hydrogen atoms in the siliconeresin (III) is from 0.01 to 0.5; (B′) an organosilicon compound havingan average of at least two silicon-bonded alkenyl groups per molecule inan amount sufficient to cure the rubber-modified silicone resin; and (C)a catalytic amount of a hydrosilylation catalyst.

Components (B′) and (C) of the sixth embodiment of the siliconecomposition are as described and exemplified above for the secondembodiment.

The concentration of component (B′) is sufficient to cure (cross-link)the rubber-modified silicone resin. The concentration of component (B′)is such that the ratio of the sum of the number of moles ofsilicon-bonded alkenyl groups in component (B′) and the silicone rubber(VII) to the number of moles of silicon-bonded hydrogen atoms in thesilicone resin (III) is typically from 0.4 to 2, alternatively from 0.8to 1.5, alternatively from 0.9 to 1.1.

Component (A″′) is a rubber-modified silicone resin prepared by reactingat least one silicone resin having the formula (R¹R⁵ ₂SiO_(1/2))_(w)(R⁵₂SiO_(2/2))_(x)(R⁵SiO_(3/2))_(y)(SiO_(4/2))_(z) (III) and at least onesilicone rubber having the formula R¹R² ₂SiO(R² ₂SiO)_(d)SiR² ₂R¹ (VII)in the presence of a hydrosilylation catalyst and an organic solvent toform a soluble reaction product, wherein R¹, R², R⁵, w, x, y, z,y+z/(w+x+y+z), and w+x/(w+x+y+z) are as described and exemplified above,and the subscript d has a value of from greater than 4 to 1,000.

The silicone resin having the formula (III) is as described andexemplified above for the second embodiment of thehydrosilylation-curable silicone composition. Also, the hydrosilylationcatalyst and organic solvent are as described and exemplified above inthe method of preparing the organohydrogenpolysiloxane resin having theformula (II). As in the previous embodiment of the silicone composition,the term “soluble reaction product” means when organic solvent ispresent, the product of the reaction for preparing component (A″′) ismiscible in the organic solvent and does not form a precipitate orsuspension.

In the formula (VII) of the silicone rubber, R¹ and R² are as describedand exemplified above, and the subscript d typically has a value of from4 to 1,000, alternatively from 10 to 500, alternatively form 10 to 50.

Examples of silicone rubbers having the formula (VII) include, but arenot limited to silicone rubbers having the following formulae:

ViMe₂SiO(Me₂SiO)₅₀SiMe₂Vi, ViMe₂SiO(Me₂SiO)₁₀SiMe₂Vi,ViMe₂SiO(PhMeSiO)₂₅SiMe₂Vi, and Vi₂MeSiO(PhMeSiO)₂₅SiMe₂Vi, wherein Meis methyl, Ph is phenyl, Vi is vinyl, and the numerical subscriptsindicate the number or each type of siloxane unit.

The silicone rubber having the formula (VII) can be a single siliconerubber or a mixture comprising two or more different silicone rubbers,each having the formula (VII).

Methods of preparing silicone rubbers containing silicon-bonded alkenylgroups are well known in the art; many of these compounds arecommercially available.

The reaction for preparing component (A″′) can be carried out in themanner described above for preparing component (A″) of the fifthembodiment of the silicone composition, except the silicone resin havingthe formula (I) and the silicone rubber having the formula (VI) arereplaced with the resin having the formula (III) and the rubber havingthe formula (VII), respectively. The mole ratio of silicon-bondedalkenyl groups in the silicone rubber (VII) to silicon-bonded hydrogenatoms in the silicone resin (III) is from 0.01 to 0.5, alternativelyfrom 0.05 to 0.4, alternatively from 0.1 to 0.3. Moreover, the siliconeresin and the silicone rubber are typically allowed to react for aperiod of time sufficient to complete the hydrosilylation reaction. Thismeans the components are typically allowed to react until at least 95mol %, alternatively at least 98 mol %, alternatively at least 99 mol %,of the silicon-bonded alkenyl groups originally present in the rubberhave been consumed in the hydrosilylation reaction, as determined byFTIR spectrometry.

The hydrosilylation-curable silicone composition of the present methodcan comprise additional ingredients, provided the ingredient does notprevent the silicone composition from curing to form a cured siliconeresin having low coefficient of thermal expansion, high tensilestrength, and high modulus, as described below. Examples of additionalingredients include, but are not limited to, hydrosilylation catalystinhibitors, such as 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexen-1-yne,3,5-dimethyl-1-hexyn-3-ol, 1-ethynyl-1-cyclohexanol,2-phenyl-3-butyn-2-ol, vinylcyclosiloxanes, and triphenylphosphine;adhesion promoters, such as the adhesion promoters taught in U.S. Pat.Nos. 4,087,585 and 5,194,649; dyes; pigments; anti-oxidants; heatstabilizers; UV stabilizers; flame retardants; flow control additives;and diluents, such as organic solvents and reactive diluents.

For example, the hydrosilylation-curable silicone composition cancontain (E) a reactive diluent comprising (i) an organosiloxane havingan average of at least two silicon-bonded alkenyl groups per moleculeand a viscosity of from 0.001 to 2 Pa·s at 25° C., wherein the viscosityof (E)(i) is not greater than 20% of the viscosity of the siliconeresin, e.g., component (A), (A′), (A″), or (A″′) above, of the siliconecomposition and the organosiloxane has the formula (R¹R²₂SiO_(1/2))_(m)(R² ₂SiO_(2/2))_(n)(R¹SiO_(3/2))_(p)(SiO_(4/2))_(q),wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀ halogen-substitutedhydrocarbyl, both free of aliphatic unsaturation, R² is R¹ or alkenyl, mis 0 to 0.8, n=0 to 1, p=0 to 0.25, q=0 to 0.2, m+n+p+q=1, and m+n isnot equal to 0, provided when p+q=0, n is not equal to 0 and the alkenylgroups are not all terminal, and (ii) an organohydrogensiloxane havingan average of at least two silicon-bonded hydrogen atoms per moleculeand a viscosity of from 0.001 to 2 Pa·s at 25° C., in an amountsufficient to provide from 0.5 to 3 moles of silicon-bonded hydrogenatoms in (E)(ii) per mole of alkenyl groups in (E)(i), wherein theorganohydrogensiloxane has the formula (HR¹₂SiO_(1/2))_(s)(R¹SiO_(3/2))_(t)(SiO_(4/2))_(v), wherein R¹ is C₁ to C₁₀hydrocarbyl or C₁ to C₁₀ halogen-substituted hydrocarbyl, both free ofaliphatic unsaturation, s is from 0.25 to 0.8, t is from 0 to 0.5, v isfrom 0 to 0.3, s+t+v=1, and t+v is not equal to 0.

Component (E)(i) is at least one organosiloxane having an average of atleast two alkenyl groups per molecule and a viscosity of from 0.001 to 2Pa·s at 25° C., wherein the viscosity of (E)(i) is not greater than 20%of the viscosity of the silicone resin of the silicone composition andthe organosiloxane has the formula (R¹R² ₂SiO_(1/2))_(m) (R²₂SiO_(2/2))_(n)(R¹SiO_(3/2))_(p)(SiO_(4/2))_(q), wherein R¹ is C₁ to C₁₀hydrocarbyl or C₁ to C₁₀ halogen-substituted hydrocarbyl, both free ofaliphatic unsaturation, R² is R¹ or alkenyl, m is 0 to 0.8, n=0 to 1,p=0 to 0.25, q=0 to 0.2, m+n+p+q=1, and m+n is not equal to 0, providedwhen p+q=0, n is not equal to 0 and the alkenyl groups are not allterminal (i.e., not all the alkenyl groups in the organosiloxane are inthe R¹R² ₂SiO_(1/2) units). Further, organosiloxane (E)(i) can have alinear, branched, or cyclic structure. For example, when the subscriptsm, p, and q in the formula of organosiloxane (E)(i) are each equal to 0,the organosiloxane is an organocyclosiloxane.

The viscosity of organosiloxane (E)(i) at 25° C. is typically from 0.001to 2 Pa·s, alternatively from 0.001 to 0.1 Pa·s, alternatively from0.001 to 0.05 Pa·s. Further, the viscosity of organosiloxane (E)(i) at25° C. is typically not greater than 20%, alternatively not greater than10%, alternatively not greater than 1%, of the viscosity of the siliconeresin in the hydrosilylation-curable silicone composition.

Examples of organosiloxanes suitable for use as organosiloxane (E)(i)include, but are not limited to, organosiloxanes having the followingformulae:

(ViMeSiO)₃, (ViMeSiO)₄, (ViMeSiO)₅, (ViMeSiO)₆, (ViPhSiO)₃, (ViPhSiO)₄,

(ViPhSiO)₅, (ViPhSiO)₆, ViMe₂SiO(ViMeSiO)_(n)SiMe₂Vi,Me₃SiO(ViMeSiO)_(n)SiMe₃, and(ViMe₂SiO)₄Si, where Me is methyl, Ph is phenyl, Vi is vinyl, and thesubscript n has a value such that the organosiloxane has a viscosity offrom 0.001 to 2 Pa·s at 25° C.

Component (E)(i) can be a single organosiloxane or a mixture comprisingtwo or more different organosiloxanes, each as described above. Methodsof making alkenyl-functional organosiloxanes are well known in the art.

Component (E)(ii) is at least one organohydrogensiloxane having anaverage of at least two silicon-bonded hydrogen atoms per molecule and aviscosity of from 0.001 to 2 Pa·s at 25° C., in an amount sufficient toprovide from 0.5 to 3 moles of silicon-bonded hydrogen atoms in (E)(ii)to moles of alkenyl groups in (E)(i), wherein the organohydrogensiloxanehas the formula (HR¹ ₂SiO_(1/2))_(s)(R¹SiO_(3/2))_(t)(SiO_(4/2))_(v),wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀ halogen-substitutedhydrocarbyl, both free of aliphatic unsaturation, s is from 0.25 to 0.8,t is from 0 to 0.5, v is from 0 to 0.3, s+t+v=1, and t+v is not equal to0.

The viscosity of organohydrogensiloxane (E)(ii) at 25° C. is typicallyfrom 0.001 to 2 Pa·s, alternatively from 0.001 to 0.1 Pa·s,alternatively from 0.001 to 0.05 Pa·s

Examples of organohydrogensiloxanes suitable for use asorganohydrogensiloxane (E)(ii) include, but are not limited to,organohydrogensiloxanes having the following formulae:

PhSi(OSiMe₂H)₃, Si(OSiMe₂H)₄, MeSi(OSiMe₂H)₃, (HMe₂SiO)₃SiOSi(OSiMe₂H)₃,and(HMe₂SiO)₃SiOSi(Ph)(OSiMe₂H)₂, where Me is methyl and Ph is phenyl.

Component (E)(ii) can be a single organohydrogensiloxane or a mixturecomprising two or more different organohydrogensiloxanes, each asdescribed above. Methods of making organohydrogensiloxanes are wellknown in the art.

The concentration of component (E)(ii) is sufficient to provide from 0.5to 3 moles of silicon-bonded hydrogen atoms, alternatively from 0.6 to 2moles of silicon-bonded hydrogen atoms, alternatively from 0.9 to 1.5moles of silicon-bonded hydrogen atoms, per mole of alkenyl groups incomponent (E)(i).

The concentration of the reactive diluent (E), components (E)(i) and(E)(ii) combined, in the hydrosilylation-curable silicone composition istypically from 0 to 90% (w/w), alternatively from 0 to 50% (w/w),alternatively from 0 to 20% (w/w), alternatively from 0 to 10% (w/w),based on the combined weight of the silicone resin, component (A), (A′),(A″), or (A″′), and the organosilicon compound, component (B) or (B′) inthe embodiments above.

The carbon nanomaterial of the nanomaterial-filled silicone compositioncan be any carbon material having at least one physical dimension (e.g.,particle diameter, fiber diameter, layer thickness) less than about 200nm. Examples of carbon nanomaterials include, but are not limited to,carbon nanoparticles having three dimensions less than about 200 nm,such as quantum dots, hollow spheres, and fullerenes; fibrous carbonnanomaterials having two dimensions less than about 200 nm, such asnanotubes (e.g., single-walled nanotubes and multi-walled nanotubes) andnanofibers (e.g., axially aligned, platelet, and herringbone or fishbonenanofibers); and layered carbon nanomaterials having one dimension lessthan about 200 nm, such as carbon nanoplatelets (e.g., exfoliatedgraphite and graphene sheet). The carbon nanomaterial can beelectrically conductive or semiconductive.

The carbon nanomaterial can also be an oxidized carbon nanomaterial,prepared by treating the aforementioned carbon nanomaterials with anoxidizing acid or mixture of acids at elevated temperature. For example,the carbon nanomaterial can be oxidized by heating the material in amixture of concentrated nitric and concentrated sulfuric acid (1:3 v/v,25 mL/g carbon) at a temperature of from 40 to 150° C. for 1-3 hours.

The carbon nanomaterial can be a single carbon nanomaterial or a mixturecomprising at least two different carbon nanomaterials, each asdescribed above.

The concentration of the carbon nanomaterial is typically from 0.0001 to99% (w/w), alternatively from 0.001 to 50% (w/w), alternatively from0.01 to 25% (w/w), alternatively from 0.1 to 10% (w/w), alternativelyfrom 1 to 5% (w/w), based on the total weight of the nanomaterial-filledsilicone composition.

Methods of preparing carbon nanomaterials are well-known in the art. Forexample, carbon nanoparticles (e.g., fullerenes) and fibrous carbonnanomaterials (e.g., nanotubes, and nanofibers) can be prepared using atleast one of the following methods: arc discharge, laser ablation, andcatalytic chemical vapor deposition. In the arc discharge process, anarc discharge between two graphite rods produces, depending on the gasatmosphere, single-walled nanotubes, multi-walled nanotubes, andfullerenes. In the laser ablation method, a graphite target loaded witha metal catalyst is irradiated with a laser in a tube furnace to producesingle- and multi-walled nanotubes. In the catalytic chemical vapordeposition method, a carbon-containing gas or gas mixture is introducedinto a tube furnace containing a metal catalyst at a temperature of from500 to 1000° C. (and different pressures) to produce carbon nanotubesand nanofibers. Carbon nanoplatelets can be prepared by theintercalation and exfoliation of graphite.

The nanomaterial-filled silicone composition can be a one-partcomposition containing the silicone resin, organosilicon compound,hydrosilylation catalyst, and carbon nanomaterial in a single part or,alternatively, a multi-part composition comprising these components intwo or more parts.

The one-part nanomaterial-filled silicone composition is typicallyprepared by combining the components of the hydrosilylaltion-curablesilicone composition, the carbon nanomaterial, and any optionalingredients in the stated proportions at ambient temperature, with orwithout the aid of an organic solvent. Although the order of addition ofthe various components is not critical if the silicone composition is tobe used immediately, the hydrosilylation catalyst is preferably addedlast at a temperature below about 30° C. to prevent premature curing ofthe composition. Also, the multi-part nanomaterial-filled siliconecomposition can be prepared by combining the components in each part.

Mixing can be accomplished by any of the techniques known in the artsuch as milling, blending, and stirring, either in a batch or continuousprocess. The particular device is determined by the viscosity of thecomponents and the viscosity of the final silicone composition.

A method of preparing a silicone resin film according to the presentinvention comprises the steps of:

coating a release liner with a nanomaterial-filled silicone composition,wherein the silicone composition comprises:

-   -   a hydrosilylation-curable silicone composition comprising a        silicone resin having an average of at least two silicon-bonded        alkenyl groups or silicon-bonded hydrogen atoms per molecule,        and    -   a carbon nanomaterial; and

heating the coated release liner at a temperature sufficient to cure thesilicone resin.

In the first step of the method of preparing a silicone resin film, arelease liner is coated with a nanomaterial-filled silicone composition,wherein the nanomaterial-filled silicone composition is as described andexemplified above.

The release liner can be any rigid or flexible material having a surfacefrom which the silicone resin film can be removed without damage bydelamination after the silicone resin is cured, as described below.Examples of release liners include, but are not limited to, silicon,quartz; fused quartz; aluminum oxide; ceramics; glass; metal foils;polyolefins such as polyethylene, polypropylene, polystyrene, andpolyethyleneterephthalate; fluorocarbon polymers such aspolytetrafluoroethylene and polyvinylfluoride; polyamides such as Nylon;polyimides; polyesters such as poly(methyl methacrylate); epoxy resins;polyethers; polycarbonates; polysulfones; and polyether sulfones. Therelease liner can also be a material, as exemplified above, having asurface treated with a release agent, such as a silicone release agent.

The release liner can be coated with the nanomaterial-filled siliconecomposition using conventional coating techniques, such as spin coating,dipping, spraying, brushing, or screen-printing. The amount of siliconecomposition is sufficient to form a cured silicone resin film having athickness of from 1 to 500 μm in the second step of the method,described below.

In the second step of the method of preparing a silicone resin film, thecoated release liner is heated at a temperature sufficient to cure thesilicone resin. The coated release liner can be heated at atmospheric,subatmospheric, or supraatmospheric pressure. The coated release lineris typically heated at a temperature of from room temperature (˜23±2°C.) to 250° C., alternatively from room temperature to 200° C.,alternatively from room temperature to 150° C., at atmospheric pressure.The coated release liner is heated for a length of time sufficient tocure (cross-link) the silicone resin. For example, the coated releaseliner is typically heated at a temperature of from 150 to 200° C. for atime of from 0.1 to 3 h.

Alternatively, the coated release liner can be heated in a vacuum at atemperature of from 100 to 200° C. and a pressure of from 1,000 to20,000 Pa for a time of from 0.5 to 3 h. The coated release liner can beheated in a vacuum using a conventional vacuum bagging process. In atypical process, a bleeder (e.g., polyester) is applied over the coatedrelease liner, a breather (e.g, Nylon, polyester) is applied over thebleeder, a vacuum bagging film (e.g., Nylon) equipped with a vacuumnozzle is applied over the breather, the assembly is sealed with tape, avacuum (e.g., 1,000 Pa) is applied to the sealed assembly, and theevacuated bag is heated as described above.

The method of preparing the silicone resin film can further comprise,before the second step of heating, applying a second release liner tothe coated release liner of the first step to form an assembly, andcompressing the assembly. The assembly can be compressed to removeexcess silicone composition and/or entrapped air, and to reduce thethickness of the coating. The assembly can be compressed usingconventional equipment such as a stainless steel roller, hydraulicpress, rubber roller, or laminating roll set. The assembly is typicallycompressed at a pressure of from 1,000 Pa to 10 MPa and at a temperatureof from room temperature (˜23±2° C.) to 50° C.

The method can further comprise the step of separating the curedsilicone resin from the release liner(s). The cured silicone resin canbe separated from the release liner by mechanically peeling the filmaway from the release liner.

The method of the present invention can further comprise forming acoating on at least a portion of the silicone resin film. Examples ofcoatings include, but are not limited to, cured silicone resins preparedby curing hydrosilylation-curable silicone resins orcondensation-curable silicone resins; cured silicone resins prepared bycuring sols of organosilsesquioxane resins; inorganic oxides, such asindium tin oxide, silicon dioxide, and titanium dioxide; inorganicnitrides, such as silicon nitride and gallium nitride; metals, such ascopper, silver, gold, nickel, and chromium; and silicon, such asamorphous silicon, microcrystalline silicon, and polycrystallinesilicon.

The silicone resin film of the present invention typically comprisesfrom 10 to 99% (w/w), alternatively from 30 to 95% (w/w), alternativelyfrom 60 to 95% (w/w), alternatively from 80 to 95% (w/w), of the curedsilicone resin. Also, the silicone resin film typically has a thicknessof from 1 to 500 μm, alternatively from 15 to 500 μm, alternatively from15 to 300 μm, alternatively from 20 to 150 μm, alternatively from 30 to125 μm.

The silicone resin film typically has a flexibility such that the filmcan be bent over a cylindrical steel mandrel having a diameter less thanor equal to 3.2 mm without cracking, where the flexibility is determinedas described in ASTM Standard D522-93a, Method B.

The silicone resin film has low coefficient of linear thermal expansion(CTE), high tensile strength, and high modulus. For example the filmtypically has a CTE of from 0 to 80 μm/m° C., alternatively from 0 to 20μm/m° C., alternatively from 2 to 10 μm/m° C., at temperature of fromroom temperature (˜23±2° C.) to 200° C. Also, the film typically has atensile strength at 25° C. of from 5 to 200 MPa, alternatively from 20to 200 MPa, alternatively from 50 to 200 MPa. Further, the siliconeresin film typically has a Young's modulus at 25° C. of from 0.5 to 10GPa, alternatively from 1 to 6 GPa, alternatively from 3 to 5 GPa.

The transparency of the silicone resin film depends on a number offactors, such as the composition of the cured silicone resin, thethickness of the film, and the type and concentration of the carbonnanomaterial. The silicone resin film typically has a transparency (%transmittance) of at least 50%, alternatively at least 60%,alternatively at least 75%, alternatively at least 85%, in the visibleregion of the electromagnetic spectrum.

The silicone resin film of the present invention has low coefficient ofthermal expansion, high tensile strength, and high modulus compared to asilicone resin film prepared from the same silicone composition absentthe carbon nanomaterial. Also, although the filled (i.e., carbonnanomaterial-containing) and unfilled silicone resin films havecomparable glass transition temperatures, the former film typicallyexhibits a smaller change in modulus in the temperature rangecorresponding to the glass transition.

The silicone resin film of the present invention is useful inapplications requiring films having high thermal stability, flexibility,mechanical strength, and transparency. For example, the silicone resinfilm can be used as an integral component of flexible displays, solarcells, flexible electronic boards, touch screens, fire-resistantwallpaper, and impact-resistant windows. The film is also a suitablesubstrate for transparent or nontransparent electrodes.

EXAMPLES

The following examples are presented to better illustrate thenanomaterial-filled silicone composition, method, and silicone resinfilm of the present invention, but are not to be considered as limitingthe invention, which is delineated in the appended claims. Unlessotherwise noted, all parts and percentages reported in the examples areby weight. The following methods and materials were employed in theexamples:

Measurement of Mechanical Properties

Young's modulus, tensile strength, and tensile strain at break weremeasured using an MTS Alliance RT/5 testing frame, equipped with a 100-Nload cell. Young's modulus, tensile strength, and tensile strain weredetermined at room temperature (˜23±2° C.) for the test specimens ofExamples 4 and 5.

The test specimen was loaded into two pneumatic grips spaced apart 25 mmand pulled at a crosshead speed of 1 mm/min. Load and displacement datawere continuously collected. The steepest slope in the initial sectionof the load-displacement curve was taken as the Young's modulus.Reported values for Young's modulus (GPa), tensile strength (MPa), andtensile strain (%) each represent the average of three measurements madeon different dumbbell-shaped test specimens from the same silicone resinfilm.

The highest point on the load-displacement curve was used to calculatethe tensile strength according to the equation:

σ=F/(wb),

where:σ=tensile strength, MPa,F=highest force, N,w=width of the test specimen, mm, andb=thickness of the test specimen, mm.

The tensile strain at break was approximated by dividing the differencein grip separation before and after testing by the initial separationaccording to the equation:

∈=100(l ₂ −l ₁)/l ₁,

where:∈=tensile strain at break, %,l₂=final separation of the grips, mm, andl₁=initial separation of the grips, mm.

Pyrograf®-III grade HHT-19 carbon nanofiber, sold by Pyrograf Products,Inc. (Cedarville, Ohio), is a heat-treated (up to 3000° C.) carbonnanofiber having a diameter of 100 to 200 nm and a length of 30,000 to100,000 nm.

Silicone Base A: a mixture containing 82% of a silicone resin having theformula (PhSiO_(3/2))_(0.75)(ViMe₂SiO_(1/2))_(0.25), where the resin hasa weight-average molecular weight of about 1700, a number-averagemolecular weight of about 1440, and contains about 1 mol % ofsilicon-bonded hydroxy groups; and 18% of1,-4-bis(dimethylsilyl)benzene. The mole ratio of silicon-bondedhydrogen atoms in the 1,-4-bis(dimethylsilyl)benzene to silicon-bondedvinyl groups in the silicone resin is 1.1:1, as determined by ²⁹SiNMRand ¹³CNMR.

Silicone Base B: a mixture containing 76% of a silicone resin having theformula (PhSiO_(3/2))_(0.75)(ViMe₂SiO_(1/2))_(0.25), where the resin hasa weight-average molecular weight of about 1700, a number-averagemolecular weight of about 1440, and contains about 1 mol % ofsilicon-bonded hydroxy groups; 9.5% of phenyltris(dimethylsiloxy)silane;and 14.5% of 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane. The moleratios of silicon-bonded hydrogen atoms in thephenyltris(dimethylsiloxy)silane to silicon-bonded vinyl groups in theSilicone Resin, and silicon-bonded hydrogen atoms in the1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane to silicon-bonded vinylgroups are each 0.55:1, as determined by ²⁹SiNMR and ¹³CNMR.

Melinex® 516, sold by Dupont Teijin Films (Hopewell, Va.), is apolyethylene-terephthalate (PET) film, which is pretreated for slip,having a thickness of 125 μm.

Example 1

This example demonstrates the preparation of a chemically oxidizedcarbon nanofiber. Pyrograf®-III carbon nanofiber (2.0 g), 12.5 mL ofconcentrated nitric acid, and 37.5 mL of concentrated sulfuric acid werecombined sequentially in a 500-mL three-neck flask equipped with acondenser, thermometer, Teflon-coated magnetic stirring bar, and atemperature controller. The mixture was heated to 80° C. and kept atthis temperature for 3 h. The mixture was then cooled by placing theflask on a layer of dry ice in a one gallon pail. The mixture was pouredinto a Buchner funnel containing a nylon membrane (0.8 μm) and thecarbon nanofibers were collected by vacuum filtration. The nanofibersremaining on the membrane were washed several times with deionized wateruntil the pH of the filtrate was equal to the pH of the wash water.After the last wash, the carbon nanofibers were kept in the funnel foran additional 15 min. with continued application of the vacuum. Then thenanofibers, supported on the filter membrane, were placed in an oven at100° C. for 1 h. The carbon nanofibers were removed from filter membraneand stored in a dry sealed glass jar.

Example 2

The oxidized carbon nanofiber of Example 1 (0.1 g) was mixed withSilicone Base A (9.9 g) in a glass vial, followed by the addition of 4.0g of heptane. The vial was placed in an ultrasonic bath for 115 min. Themixture was then subjected to centrifugation at 1500 rpm for 30 min. Thesupernatant was transferred to a clean vial and kept under vacuum (45 mmHg) at 50° C. for 90 min. to remove most of the heptane.

Example 3

The oxidized carbon nanofiber of Example 1 (0.04 g) was mixed withSilicone Base B (20.0 g) in a glass vial, followed by the addition of8.0 g of heptane. The vial was placed in an ultrasonic bath for 115 min.The mixture was then subjected to centrifugation at 1500 rpm for 30 min.The supernatant was transferred to a clean vial and kept under vacuum(45 mm Hg) at 50° C. for 90 min. to remove most of the heptane.

Example 4

The silicone composition of Example 2 (4.0 g) was mixed with 0.05 g of acatalyst consisting of a platinum(0) complex of1,3-divinyl-1,1,3,3,-tetramethyldisiloxane in toluene, and containing1000 ppm of platinum. The resulting composition (2.0 g) was applied onthe surface of a Melinex® 516 PET film (8 in.×11 in.). An identical PETfilm was placed on top of the coating with the release agent-treatedside in contact with the silicone composition. The stack was then passedbetween two stainless steel bars separated by a distance of 300 μm. Thelaminate was heated in an oven according to the following cycle: roomtemperature to 80° C. at 2° C./minute, 80° C. for 30 min., 80° C. to120° C. at 2° C./minute, 120° C. for 60 min. The oven was turned off andthe laminate was allowed to cool to room temperature inside the oven.The upper PET film was separated (peeled away) from the silicone resinfilm, and the silicone resin film was then separated from the lower PETfilm. The mechanical properties of the silicone resin film are shown inTable 1.

Example 5

A silicone resin film was prepared according to the method of Example 4,except the silicone composition of Example 3 was substituted for thesilicone composition of Example 2. The mechanical properties of thesilicone resin film are shown in Table 1.

TABLE 1 Tensile Strain Thickness Tensile Strength Young's Modulus atBreak Ex. (mm) (MPa) (MPa) (%) 4 0.117 8.4 328.9 49.7 5 0.100 12.4 591.311.6

1. A nanomaterial-filled silicone composition, comprising: ahydrosilylation-curable silicone composition comprising a silicone resinhaving an average of at least two silicon-bonded alkenyl groups orsilicon-bonded hydrogen atoms per molecule; and a carbon nanomaterial.2. The nanomaterial-filled silicone composition according to claim 1,wherein the hydrosilylation-curable silicone composition comprises (A) asilicone resin having the formula (R¹R² ₂SiO_(1/2))_(w)(R²₂SiO_(2/2))_(x)(R¹SiO_(3/2))_(y)(SiO_(4/2))_(z) (I), wherein R¹ is C₁ toC₁₀ hydrocarbyl or C₁ to C₁₀ halogen-substituted hydrocarbyl, both freeof aliphatic unsaturation, R² is R¹ or alkenyl, w is from 0 to 0.8, x isfrom 0 to 0.6, y is from 0 to 0.99, z is from 0 to 0.35, w+x+y+z=1,y+z/(w+x+y+z) is from 0.2 to 0.99, and w+x/(w+x+y+z) is from 0.01 to0.8, provided the silicone resin has an average of at least twosilicon-bonded alkenyl groups per molecule; (B) an organosiliconcompound having an average of at least two silicon-bonded hydrogen atomsper molecule in an amount sufficient to cure the silicone resin; and (C)a catalytic amount of a hydrosilylation catalyst.
 3. Thenanomaterial-filled silicone composition according to claim 1, whereinthe hydrosilylation-curable silicone composition comprises (A′) asilicone resin having the formula (R¹R⁵ ₂SiO_(1/2))_(w)(R⁵₂SiO_(2/2))_(x)(R⁵SiO_(3/2))_(y)(SiO_(4/2))_(z) (III), wherein R¹ is C₁to C₁₀ hydrocarbyl or C₁ to C₁₀ halogen-substituted hydrocarbyl, bothfree of aliphatic unsaturation, R⁵ is R¹ or —H, w is from 0 to 0.8, x isfrom 0 to 0.6, y is from 0 to 0.99, z is from 0 to 0.35, w+x+y+z=1,y+z/(w+x+y+z) is from 0.2 to 0.99, and w+x/(w+x+y+z) is from 0.01 to0.8, provided the silicone resin has an average of at least twosilicon-bonded hydrogen atoms per molecule; (B′) an organosiliconcompound having an average of at least two silicon-bonded alkenyl groupsper molecule in an amount sufficient to cure the silicone resin; and (C)a catalytic amount of a hydrosilylation catalyst.
 4. Thenanomaterial-filled silicone composition according to claim 1, whereinthe hydrosilylation-curable silicone composition comprises (A) asilicone resin having the formula (R¹R² ₂SiO_(1/2))_(w)(R²₂SiO_(2/2))_(x)(R¹SiO_(3/2))_(y)(SiO_(4/2))_(z) (I); (B) anorganosilicon compound having an average of at least two silicon-bondedhydrogen atoms per molecule in an amount sufficient to cure the siliconeresin; (C) a catalytic amount of a hydrosilylation catalyst; and (D) asilicone rubber having a formula selected from (i) R¹R² ₂SiO(R²₂SiO)_(a)SiR² ₂R¹ (IV) and (ii) R⁵R¹ ₂SiO(R¹R⁵SiO)_(b)SiR¹ ₂R⁵ (V);wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀ halogen-substitutedhydrocarbyl, both free of aliphatic unsaturation, R² is R¹ or alkenyl,R⁵ is R¹ or —H, subscripts a and b each have a value of from 1 to 4, wis from 0 to 0.8, x is from 0 to 0.6, y is from 0 to 0.99, z is from 0to 0.35, w+x+y+z=1, y+z/(w+x+y+z) is from 0.2 to 0.99, and w+x/(w+x+y+z)is from 0.01 to 0.8, provided the silicone resin and the silicone rubber(D)(i) each have an average of at least two silicon-bonded alkenylgroups per molecule, the silicone rubber (D)(ii) has an average of atleast two silicon-bonded hydrogen atoms per molecule, and the mole ratioof silicon-bonded alkenyl groups or silicon-bonded hydrogen atoms in thesilicone rubber (D) to silicon-bonded alkenyl groups in the siliconeresin (A) is from 0.01 to 0.5.
 5. The nanomaterial-filled siliconecomposition according to claim 1, wherein the hydrosilylation-curablesilicone composition comprises (A′) a silicone resin having the formula(R¹R⁵ ₂SiO_(1/2))_(w)(R⁵ ₂SiO_(2/2))_(x)(R⁵SiO_(3/2))_(y)(SiO_(4/2))_(z)(III); (B′) an organosilicon compound having an average of at least twosilicon-bonded alkenyl groups per molecule in an amount sufficient tocure the silicone resin; (C) a catalytic amount of a hydrosilylationcatalyst; and (D) a silicone rubber having a formula selected from (i)R¹R² ₂SiO(R² ₂SiO)_(a)SiR² ₂R¹ (IV) and (ii) R⁵R¹ ₂SiO(R¹R⁵SiO)_(b)SiR¹₂R⁵ (V); wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀halogen-substituted hydrocarbyl, both free of aliphatic unsaturation, R²is R¹ or alkenyl, R⁵ is R¹ or —H, subscripts a and b each have a valueof from 1 to 4, w is from 0 to 0.8, x is from 0 to 0.6, y is from 0 to0.99, z is from 0 to 0.35, w+x+y+z=1, y+z/(w+x+y+z) is from 0.2 to 0.99,and w+x/(w+x+y+z) is from 0.01 to 0.8, provided the silicone resin andthe silicone rubber (D)(ii) each have an average of at least twosilicon-bonded hydrogen atoms per molecule, the silicone rubber (D)(i)has an average of at least two silicon-bonded alkenyl groups permolecule, and the mole ratio of silicon-bonded alkenyl groups orsilicon-bonded hydrogen atoms in the silicone rubber (D) tosilicon-bonded hydrogen atoms in the silicone resin (A′) is from 0.01 to0.5.
 6. The nanomaterial-filled silicone composition according to claim1, wherein the hydrosilylation-curable silicone composition comprises(A″) a rubber-modified silicone resin prepared by reacting a siliconeresin having the formula (R¹R² ₂SiO_(1/2))_(w)(R²₂SiO_(2/2))_(x)(R¹SiO_(3/2))_(y)(SiO_(4/2))_(z) (I) and a siliconerubber having the formula R⁵R¹ ₂SiO(R¹R⁵SiO)_(c)SiR¹ ₂R⁵ (VI) in thepresence of a hydrosilylation catalyst and, optionally, an organicsolvent to form a soluble reaction product, wherein R¹ is C₁ to C₁₀hydrocarbyl or C₁ to C₁₀ halogen-substituted hydrocarbyl, both free ofaliphatic unsaturation, R² is R¹ or alkenyl, R⁵ is R¹ or —H, subscript chas a value of from greater than 4 to 1,000, w is from 0 to 0.8, x isfrom 0 to 0.6, y is from 0 to 0.99, z is from 0 to 0.35, w+x+y+z=1,y+z/(w+x+y+z) is from 0.2 to 0.99, and w+x/(w+x+y+z) is from 0.01 to0.8, provided the silicone resin (I) has an average of at least twosilicon-bonded alkenyl groups per molecule, the silicone rubber (VI) hasan average of at least two silicon-bonded hydrogen atoms per molecule,and the mole ratio of silicon-bonded hydrogen atoms in the siliconerubber (VI) to silicon-bonded alkenyl groups in silicone resin (I) isfrom 0.01 to 0.5; (B) an organosilicon compound having an average of atleast two silicon-bonded hydrogen atoms per molecule in an amountsufficient to cure the rubber-modified silicone resin; and (C) ahydrosilylation catalyst.
 7. The nanomaterial-filled siliconecomposition according to claim 1, wherein the hydrosilylation-curablesilicone composition comprises (A′″) a rubber-modified silicone resinprepared by reacting a silicone resin having the formula (R¹R⁵₂SiO_(1/2))_(w)(R⁵ ₂SiO_(2/2))_(x)(R⁵SiO_(3/2))_(y)(SiO_(4/2))_(z) (III)and a silicone rubber having the formula R¹R² ₂SiO(R² ₂SiO)_(d)SiR² ₂R¹(VII) in the presence of a hydrosilylation catalyst and, optionally, anorganic solvent to form a soluble reaction product, wherein R¹ is C₁ toC₁₀ hydrocarbyl or C₁ to C₁₀ halogen-substituted hydrocarbyl, both freeof aliphatic unsaturation, R² is R¹ or alkenyl, R⁵ is R¹ or —H,subscript d has a value of from greater than 4 to 1,000, w is from 0 to0.8, x is from 0 to 0.6, y is from 0 to 0.99, z is from 0 to 0.35,w+x+y+z=1, y+z/(w+x+y+z) is from 0.2 to 0.99, and w+x/(w+x+y+z) is from0.01 to 0.8, provided the silicone resin MD has an average of at leasttwo silicon-bonded hydrogen atoms per molecule, the silicone rubber(VII) has an average of at least two silicon-bonded alkenyl groups permolecule, and the mole ratio of silicon-bonded alkenyl groups in thesilicone rubber (VII) to silicon-bonded hydrogen atoms in the siliconeresin (III) is from 0.01 to 0.5; (B′) an organosilicon compound havingan average of at least two silicon-bonded alkenyl groups per molecule inan amount sufficient to cure the rubber-modified silicone resin; and (C)a catalytic amount of a hydrosilylation catalyst.
 8. Thenanomaterial-filled silicone composition according to any of thepreceding claims, wherein the hydrosilylation-curable siliconecomposition further comprises (E) a reactive diluent comprising (i) anorganosiloxane having an average of at least two silicon-bonded alkenylgroups per molecule and a viscosity of from 0.001 to 2 Pa·s at 25° C.,wherein the viscosity of (E)(i) is not greater than 20% of the viscosityof the silicone resin of the silicone composition and the organosiloxanehas the formula (R¹R² ₂SiO_(1/2))_(m)(R²₂SiO_(2/2))_(n)(R¹SiO_(3/2))_(p)(SiO_(4/2))_(q), wherein R¹ is C₁ to C₁₀hydrocarbyl or C₁ to C₁₀ halogen-substituted hydrocarbyl, both free ofaliphatic unsaturation, R² is R¹ or alkenyl, m is 0 to 0.8, n=0 to 1,p=0 to 0.25, q=0 to 0.2, m+n+p+q=1, and m+n is not equal to 0, providedwhen p+q=0, n is not equal to 0 and the alkenyl groups are not allterminal, and (ii) an organohydrogensiloxane having an average of atleast two silicon-bonded hydrogen atoms per molecule and a viscosity offrom 0.001 to 2 Pa·s at 25° C., in an amount sufficient to provide from0.5 to 3 moles of silicon-bonded hydrogen atoms in (E)(ii) per mole ofalkenyl groups in (E)(i), wherein the organohydrogensiloxane has theformula (HR¹ ₂SiO_(1/2))_(s)(R¹SiO_(3/2))_(t)(SiO_(4/2))_(v), wherein R¹is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀ halogen-substituted hydrocarbyl,both free of aliphatic unsaturation, s is from 0.25 to 0.8, t is from 0to 0.5, v is from 0 to 0.3, s+t+v=1, and t+v is not equal to
 0. 9. Thenanomaterial-filled silicone composition according to claim 2, 4, or 6,wherein the organosilicon compound of component (B) is anorganohydrogenpolysiloxane resin having the formula (R¹R⁴₂SiO_(1/2))_(w)(R⁴ ₂SiO_(2/2))_(x)(R¹SiO_(3/2))_(y)(SiO_(4/2))_(z) (II),wherein R¹ is C₁ to C₁₀ hydrocarbyl or C₁ to C₁₀ halogen-substitutedhydrocarbyl, both free of aliphatic unsaturation, R⁴ is R¹ or anorganosilylalkyl group having at least one silicon-bonded hydrogen atom,w is from 0 to 0.8, x is from 0 to 0.6, y is from 0 to 0.99, z is from 0to 0.35, w+x+y+z=1, y+z/(w+x+y+z) is from 0.2 to 0.99, and w+x/(w+x+y+z)is from 0.01 to 0.8, provided at least 50 mol % of the groups R⁴ areorganosilylalkyl.
 10. The nanomaterial-filled silicone compositionaccording to claim 1, wherein the carbon nanomaterial is selected fromcarbon nanoparticles, fibrous carbon nanomaterials, and layered carbonnanomaterials.
 11. The nanomaterial-filled silicone compositionaccording to claim 1, wherein the concentration of the carbonnanomaterial is from 0.001 to 50% (w/w), based on the total weight ofthe nanomaterial-filled silicone composition.
 12. A method of preparinga silicone resin film, the method comprising the steps of: coating arelease liner with a nanomaterial-filled silicone composition, whereinthe silicone composition comprises: a hydrosilylation-curable siliconecomposition comprising a silicone resin having an average of at leasttwo silicon-bonded alkenyl groups or silicon-bonded hydrogen atoms permolecule, and a carbon nanomaterial; and heating the coated releaseliner at a temperature sufficient to cure the silicone resin.
 13. Themethod according to claim 12, wherein the carbon nanomaterial isselected from carbon nanoparticles, fibrous carbon nanomaterials, andlayered carbon nanomaterials.
 14. The method according to claim 12,wherein the concentration of the carbon nanomaterial is from 0.001 to50% (w/w), based on the total weight of the nanomaterial-filled siliconecomposition.
 15. (canceled)
 16. The method according to claim 12,further comprising forming a coating on at least a portion of thesilicone resin film.
 17. The method according to claim 16, wherein thecoating is a cured silicone resin.
 18. A silicone resin film preparedaccording to the methods of claims 12 or 16.